A service appliance is installed between production servers running service applications and service users. The production servers and their service applications provide services to the service users. In the event that a production server is unable to provide its service to users, the service appliance can transparently intervene to maintain service availability. To maintain transparency to service users and service applications, service users are located on a first network and production servers are located on a second network. The service appliance assumes the addresses of the service users on the second network and the addresses of the production servers on the first network. Thus, the service appliance obtains all network traffic sent between the production server and service users. While the service application is operating correctly, the service appliance forwards network traffic between the two networks using various network layers.